1. Field of Invention
The present invention relates to a cephalogram image analysis method. More particularly, the present invention relates to a cephalogram image analysis method used for transforming cephalograms into tracings.
2. Description of Related Art
In orthodontic treatment, cephalometry is quite an important metrology technique for analyzing patient's anatomical structure and evaluating the treatment effects. Cephalograms are X-ray films taken at a head portion, and the X-ray films (cephalograms) of posteroanterior view and lateral view are frequently used in clinic.
Referring to FIG. 1A to FIG. 1C, FIG. 1A illustrates a lateral cephalogram 10 and a posteroanterior cephalogram 12; FIG. 1B illustrates a tracing 20 of the lateral cephalogram 10, and a tracing 22 of the posteroanterior cephalogram 12; and FIG. 1C illustrates the tracing 20 of the lateral cephalogram 10 with landmarks shown thereon. When at least one cephalograms (such as the lateral cephalogram 10 and the posteroanterior cephalogram 12) are in use, the anatomical features and landmarks of the cephalograms have to be drawn on tracing papers, thereby obtaining tracings (such as the tracing 20 and the tracing 22). The so-called “landmarks” stand for a set of feature points defined from anatomical viewpoints for use in marking an anatomical structure, and can be used for analyzing the geometrical features of the anatomical structure, such as landmarks S, Po, Na, PNS, UIA, ANS, A, MI, LIE, UIE, LIA, B, Pog, Gn, Me, etc. as shown in FIG. 1C. Those landmarks are well known to those who are skilled in the art, and thus are not described in detail herein. The tracing paper is a piece of acetate similar to a translucent paper. In a conventional clinical and cephalometric assessment, a tracing paper is manually overlaid on a cephalogram, and then a set of landmarks and their associated feature curves are drawn and marked one by one so as to form a tracing.
Various cephalogram analysis methods are used to define geometrically related parameters by referring to the positions of these landmarks, thereby computing the measures of the anatomical structure, such as the data of distances, angles, etc. However, such manual drawing process is quite time and effort consuming, and since the definitions of landmarks mostly belong to semantic description, the expert experience of the plotter (physician) will greatly influence the accuracy of the tracing.
Hence, there is a need to provide an automated cephalogram image analysis method for effectively transforming a cephalogram into a tracing, thereby overcoming the disadvantages of the conventional skill.